Effects of Oxidation Ambient and Low Temperature Post Oxidation Anneal on the Silicon/Oxide Interface Structure and the Electrical Properties of the Thin Gate Oxide

Abstract

Electrical properties of ultra thin gate oxide in thickness of 4 to 10 nm have been evaluated, manufactured either by wet or dry oxidation process. The relationship between silicon/oxide interfacial structure and the electrical properties was analyzed. In addition, the effect of post oxidation annealing (POA) temperature on improvement of the electrical characteristics of the gate oxide has been evaluated when the temperature was lower than 950°C, the conventional POA temperature. The leakage current of the ultra thin gate oxide was found to increase as the thickness decreased. The accelerated degradation of breakdown characteristics was observed as the thickness decreased below 7 nm. The physical properties of the silicon/oxide interface were found to depend on oxidation ambient and POA temperature. The wet oxidation process resulted in a smoother surface than the dry oxidation process did. The POA treatment further decreased the micro-roughness of the silicon/oxide interface. The electrical properties of the gate oxide were found to be closely related to the micro-roughness of the silicon/oxide interface. Good electrical properties were obtained for the gate oxide manufactured by the wet oxidation process followed by the POA treatment at 850°C.